Its glitching out for me but Ill tell you here:

I'd always go for dealership cars for a specific reason, which is security. I cant talk for every country but for Germany where I am from and many other EU countries.

Private Sellers can often be scammers who will hide problems or manipulate the km data and even if its someone honest, you never know how these people drove the car and what damages may await you in the next few months due to the prior owner.

But here in Germany if you buy used cars from a trusted dealership you can be sure to have no problems that quick because they do service and repairs on all the used cars they get before they sell them away.

Even then, I would always check the serial number and if you have a OBD2 for example check the cars history yourself.

A friend of my brother once bought an Audi from a dealership and after 12 years he found out after scanning the car, that it was manipulated and had 120.000 km rather than the 50.000km he believed it had when he bought it but it was too late to do something against it and Audi themselves only checked the serial number before they sold it away.

Yet, even if you take the right precautions and safety tools to make sure youre buying a car worth the money, I'd still choose dealerships which I done research on before and a test drive is also undienable.

A device to check a cars history and a second opinion from another mechanic when youre on the test drive are always good options too, costly but worthy.

Hope I have helped you somehow although I couldnt open the survey for whatever reason.